US President Donald Trump has said North Korea’s nuclear and missile program is now “very, very far advanced,” and placed blame on former President Barack Obama and others for not doing enough to contain it.

“This should have been handled 25 years ago, it should have been handled 20 years ago, and 10 years ago, and five years ago,” Trump told Fox News’ Sean Hannity in an interview on Wednesday.

“It should have been handled by numerous – not just Obama, but certainly President Obama should have taken care of it. Now it’s at a point where it’s very, very far advanced,” he added. “Something has to be done. We can’t allow this to happen.”

Last month, Dr. Abdul Qadeer Khan, the father of Pakistan’s nuclear weapons program, also said that North Korea’s nukes are very sophisticated, and much better than Pakistan’s.

“Their scientists are highly capable, and most of them have studied in Russia,” Khan told BBC Urdu, according to a translation of it published by dawn.

Khan made the comments on September 4, a day after North Korea said it successfully tested a hydrogen bomb.

Dr. Abdul Qadeer Khan

“Hydrogen bombs are much more powerful than atom bombs. For instance, an atom bomb may destroy the area in the radius of 1.5 to two kilometers, but a hydrogen bomb can devastate an entire city,” the scientist said.

In the recent months, tensions between the United States and North Korea have risen to new heights. Trump has often verbally attacked the North Korean leadership, and repeatedly threatened military action against the Asian nation.

Continuing his aggressive rhetoric against North Korean officials last weekend, Trump claimed that a diplomatic approach over the past 25 years “hasn’t worked” and that Pyongyang has made “fools of US negotiators.”

In a speech to the UN General Assembly last month, Trump warned North Korean leader Kim Jong-un that the United States, if threatened, would “totally destroy” his country of 26 million people.

In response, Kim said Trump will “pay dearly” for threatening to destroy North Korea.

He added that Trump is “a rogue and a gangster fond of playing with fire,” who is “unfit to hold the prerogative of supreme command of a country.”

Kim described the US president as “mentally deranged” and warning he would “pay dearly” for threatening to destroy his country.

Bob Corker, the Republican chairman of the Senate Foreign Relations Committee, said in an interview with The New York Times on Sunday that Trump’s harsh rhetoric against North Korea and others could put the US “on the path to World War III.”

Meanwhile, Democratic Senator Brian Schatz from Hawaii on Sunday night expressed fears that Trump’s policy of brinkmanship against North Korea could lead the United States toward an accidental war.

The senator complained that the president treats the country like “a reality show” and acts “like he’s doing ‘The Apprentice’ or something.”

North Korea has conducted several nuclear tests and missile test-launches in response to US threats against the country.

The North Korean leader ordered the production of more rocket warheads and engines in September, shortly after the United States suggested that its threats of military action and sanctions were having an impact on Pyongyang’s behavior.